Regulating the bulk density of coke-oven charges



June 19, 1945. v F. D. LOHR ETAL 2,378,420

REGULATING THE BULK DENSITY OF COKE `OVEN CHARGES Filed June s, 1941 2 sheets-sheet 1 III- 2.?/ rloIsTune Com..

' INVENTQRS. F2eemAN- D ooLlTTLe Lol-uz 8e Gasen-r Vmcenr MC Gon.

June 19, 1945. F. D. I OHR Ei-AL 2,378,420

I REGULATING THE BULK DENSITY OF COKE OVEN CHARGES Filed June 9, 1941 2 sheets-sheet 2 uam au Non .Ll-Imam v HJVEBJTORS.y -F1zEMAH DooLxTTLr.- Lomzo BY GILBERT VINCENT MC Gunn.;

Patented June 19, 1945 REGULATING THE BULK DENSITY F COKE-OVEN CHARGES Freeman Doolittle Lohr, East Orange, and Gilbert Vincent McGurl, Newark, N. J., assignors, by mesne assignments, to Koppers Company, lne., a corporation of Delaware Application `lune 9, 194i, Serial No. 397,154

-3 Claims.

The present invention relates to the coking of coals and comprehends more particularly improvements in the preparing of coking coals for coke-oven charges whereby those variations in their buik densities which are occasioned more especially b y uctuations in superficial-moisture content can be conveniently and cheaply adjusted to provide the coals with a predeterminable, preferred bulk density within that range vof supercial-moisture contents generally found in coals employed in the coking art.

An object of the present improvement is the provision of novel means whereby those variations in the bulk density of a coal caused by changes in its superficial-moisture content can be obviatedy so that the same weight of coal can be always contained in the levelled charge of a coke oven.

A further object of improvement is the provision of means whereby the lower bulk density of a moist coal, or of coal mixtures, can be regularly increased, so that greater quantities thereof are chargeable into coke-oven coking chambers than would otherwise be possible.

A further object of invention is the provision of means for promoting maintenance of uniform operating conditions both in a coke-oven battery and in the associated by-product recovery system and realization of the attendant advantages to the structure and its operation.

The invention has for further objects such other improvements and such other operating advantages or results as may be found to obtain in the processes or apparatus hereinafter described or claimed.

It is well known in the art that variations in its surface or superlcial-moisture content cause Y changes in the weight per cubic foot or bulk density of a coal. The charging from day-today of substantially uniform weights of coal or coal mixtures into the same coke ovens is practically impossible when, for example, the coals for one days charging are taken from a storage are treated with relatively small amounts of.

agents that are effective to reducel ,the iluillng or bulking effect of this moisture and the coal particles can automatically become more closely packed without resorting to other measures. It has now been discovered that coals having more than about one per cent of superficial-moisture content, when treated with surprisingly small amounts of oily materials, such as bunker oils, absorbent oils of the type employed for the recovery of coke-oven light oil, creosote oils, Watergas tars, and coal tars, oil emulsions, and other petroleum-derived oils and mixtures thereof with other materials having a varying oil content and viscosity, or the like, exhibit an increase in their existing bulk densities without apparent reduction in the moisture content.` Oily materials ranging widely in viscosity from about 40 seconds vof supercial waterbetween the coal particles below its normal value are also suitable for the purpose, as are also solutions 0r suspensions of wetting agents in oils orbily materials. It has been found that, in general, materials adapted to wet the surface of moist coal in preference to the superficial or surface water of the coal itself or todecrease the wettability of coal by such moisture, can be employed to alter the bulk density of moist coal and provide the benecialfand novel results of the present invention. It is to be understood that where an oil is employed to eiect said novel results, an oily material or wetting agent or a combination of an oily material and a wetting agent can be used to produce similar results.

In the practice of the present improvement,

finely pulverized coking coals, or nely pulverized coal mixtures, are prepared in the 4usual manner for carbonization in coke ovens. By the term finely pulverized coal, as used herein and in'. the following claims, is meant coal of .the flneness of pulverizved coal that is conventionally used for coking purposes in the divers ovens of by-product coke-ovens. Such a coal is one of the neness produced by crushing in a conventional hammer l vmill of conventional coke-oven by-product cokes 4oven plants, before 'passing over conveyor belts, as hereinafter described. -Preferahly,;at ,a point preferably just prior to admission of the coal into the hammer mill there is added to said coal the preferred quantity of an oily material or a solution of a wetting agent. The benecial effects of the present invention can be secured by the use of wetting agents or any one of a variety of oils or: oily materials. The rate of ow of the so-added bonized.

The bulk densities of a coal or coal mixture having a supercial-moisture content in excess of one per cent, will generally be found to reach a maximum value at some point where the amount of added oil is less than one per cent by Weight, thereafter decreasing with further additlons of said oil. It is interesting to note that the addition of an oil to dry coal or coal of which the superficial-moisture content is less than about one per cent, decreases the bulk density, the amount of said decrease being at a maximum when substantially one per cent of said oil, or the like, has been added. A positive control of bulk densities of coal within narrow limits by means of small additions of oil, or the like, is possible, and is one of the novel features of the present invention and diers from any small effeet incidental to the prior use of larger quantities, for example 2 to 3 per cent by weight, of oily materials on coal for the purposeof increasing the hydrocarbon content of the gas resulting from the carbonization of such oil-coal mixture, or for dustproong, or the like.

The quantity of an oil, of an. oily material, or of a wetting agent (the latter being preferably employed in a uidmedium) that is necessary to be added to coal or coal mixtures for realization of the benefits of the presentimprovement, varies within narrow limits and can be determined sim. ply and easily by empirical methods. The moisture content of a portion of the to-be-charged coking coal is rst determined, after which further portions'of said charge are each thoroughly admixed with a different quantity less than one l per cent by Weight of a preferred oil. Thereafter the bulk densities of said portions are determined by a standard test, as for example by the A. S. T. M. (D291-1929) method for 'cubic-foot weights of coal in box tests.

For simplicity and easy reference, a curve can be drawn by plotting the so-determined values where the bulk densityof the coking charges sometimes varied as much as ten pounds per cubic foot, in the day-to-day operation, as a result of changes in the moisture content of said coking charges from about 4.5 per cent to less than about 1 per cent. Separate samples of said coking charge having a 4.5 per cent moisture content were first admixed'with 1/1%, 1/s%, 1/2%, 1% and 2% by weight respectively of an oil admixture having a, viscosity of about 150 seconds at100" F. (Saybolt Universal). 'I'he so-treated samples and one untreated sample were then tsted according to the A. S. T. M. method to determine their respective bulk densities. This was followed by like tests of similar coking charges of 2.9 per cent and 0.9 per cent moisture content respectively, excepting only that, in the case of the coking charge containing 2.9 per cent moisture no tests were made with additions of 1A@ per cent and 1/8 per cent of said oil admixture. The obtained bulk-density values, fully identified in the following tabulation, were then plotted as the abscissas on the graph paper of Figure l. and the corresponding values for per cent-weight of oil admixture were plotted as the ordinates, the respective curve being thereafter drawn through the points Where said corresponding absoissas and ordinates intersected. It is obvious from a study of Figure 1 that a. horizontal line drawn through the value for bulk density'of 46 pounds per cubic foot will intersect the so-drawn curves. The coking charges in said coke-oven plant were successfully stabilized by mixing with the coal accordingly as its contents of superficial moisture varied, those indicated oil admixtures required to maintain the same at a bulk'density of about 46 pounds per cubic foot with the result that, from day to day, the levelled coke-oven charges always contained the same weight of coal, and the coke and the gas and other yields of by-products became substantially uniform and an established, heating schedule was maintainable with importantly reduced regulation and control. The following tabulation gives the results of the abovefor bulk density, in pounds per cubic foot, corresponding to the different added weights of an oil to a coal or coking charge. This procedure is clearly-illustrated by a glance at the curves shown in Fig. l. For example, curve I was drawn from the results tabulated below and obtained after following the above-described procedure for a coking charge having a moisture content of 4.5 per cent. Curves II, III and IV are a graphic illustration of results obtained with the same procedure applied to similar coking charges varying only in their moisture contents, which were 2.9 per cent, 0.9v per cent and 3.1 per cent respectively. The investigation resulting in the following tabulation and the illustrated curves of Fig. 1 was made to stabilize the quantity of coal described empirical tests for bulk densities with oil admixtures.

Curve I lCurve II Curve HI Curve IV Added Bulk densi- Bulk densl- Bulk densi- Bulk densiou ep ties in ties 1n ties ties in cenby pounds per pounds per pounds per pounds per w61 ht cubic foot cnblc foot cnbic foot cubic foot g with 4.5% with 2.9% with 0.9% with 3.1%

moisture moisture moisture moisture content content content content N0 oil--. 41. 5 4.3. 4 52. 5 42. 4 Me 45. 6 51. 8 48. 2 le-; 46. 0 50. 6 49. 0 u 45. s 47. 4 49. 7 47. 2 $5 45. 4 46. 2 48. l 45. i 1 44.2 45. o 46 .1 45.4 2 43. l 43. 0 43. 6 44. 5

charged daily in a by-product coke-oven plant It has been found and it should be emphasized with particularity that maximum values for bulk density of any coal, or coal mixture, containing more than about one percent of superficial moisdrocarbon content of gas evolved from the coal during carbonization. As is clearly evident from the curves I, lII and IV, a maximum bulk density in a moist coal usually results from the addition, within rather narrow limits, of less than about one per cent of an oil, or the like. By means of empirical data, that are determined as above described and graphically illustrated in Figure 1, and showing how bulk density, for any specific coal or coal mixture, alters with divers oil and moisture contents, a coke-plant operator can quickly and easily determine the quantity of oil necessary to be added thereto to establish either a maximum or a preferred bulk densitytherein, if its moisture content is known. Such data also enable him, by adding varying quantities of oil that are below substantially one per cent by weight and are adjusted to the uctuating moisture content of the coal, so to stabilize his coke-oven operation that the levelled cokeoven charges will always have substantially the same bulk density and consequently the same weight of-coal regardless of their moisture content. This day-to-day charging of substantially the. same Weight of coal into the ovens, made possible by the novel features of the present invention, tends to simplify the heating of the coking chambers and permits an operator easily to' establish and maintain for long periods the same heating conditions'with resultant decreased wear and tear on the structure of the whole coke-oven battery. 'I'his improvement in operation is further reflected in simplied control and regulation of apparatus employed in the. recovery of by-products and in improved maintenance of the apparatus employed therefor. It is to be understood that when changes are made, as for example in the oil, the wetting agent or other oily material used, orare made in the coal or coals charged, or in their pulverization, or in their proportions in the mixture, that the above-described l empirical determinations should be re -determined if the optimum conditions and results are to be obtained. f

'It is interesting to note, as is clearly shown by reference to curve III of Figure 1, and also to stress in consequence of its practical importance is dry (less than about one per cent of superficial moisture) either water or oil can be employed as a bulking agent to bring about a decrease in bulk density, and if the latter has been used for the purpose subsequent additions of water eiect'an increase in the bulk density, whereas if the former (water) has been employed, further additions'of water will effect only a further decrease of bulk density; if the coal to be treated contains more than about one per cent of water, ad

dtions of small amounts of oil always increase the bulk density Whereas the opposite effect is produced with furtherwater-additions up to a water contentof about 6 to 8 per cent; and a moist coal that has had a bulk density established by small additions of oil can have that density decreased by further additions of water. Thus, by means of additions of oil and water to a coal in a sequence that is consistent with its characteristics it is possible to adjust or to alter its bulk density within relatively precise limits.

While oils andoily materials, as above mentioned, are preferred because they are easily available and convenient to employ -in a by-product coke-oven plant, it is also possible to utilize wetting agents. to secure the unique results made' possible by the present improvement. Numerous commercial wetting agents occur as uids or in solid or semi-solid form and can be employed for the stated purpose. If said wetting agents are manufactured'in the form of solids, semi-solids, or the like, it is preferred for ease in handling and admixing with coal, to employ themas solutions or suspensions in uid media, as for ex'- ample in water, in oily materials, or in other inorganic or organic solvents. The preferred results can also be achieved by employing in sequence oily materials and wetting agents in the stated or iny f reverse order. An example of a wetting agent that for purposes of coal carbonization that, in the case of a coal, or of a coal mixture, containing less than about one per cent of superficial moisture the converse of the above-described phenomenon takes place; that is, with coal having less than about one per cent of superficial moisture, additions thereto of smallamounts of oil, oily materiaL-or the like, which in the case of a wetter coal would increase the bulk density, bring about instead only a .decrease in bulk density.

For coals that are destined for carboniz'ation in` coke-ovens this phenomenon is useful as a means of reducing the bulk density of the drier coals-and especially of those that have a tendency to expand in the coking chambers, and has thelbeneilcial advantage that the bulk-density decrease can be brought about by a medium that in the carbonization process is cracked to produce combustible gas which, at least in part, makes up for lesser gas vvolume produced by the reduced weight A `of coal in an oven-charge Aof decreased bulk density and in this respect is superior to water which has been used in the priorart for thepurpose. f

From the above-given,l it becomes obvious that by means of appropriate additions of water and of oil to a coal its bulk density can be relatively precisely adjusted to a preferred value: if the coal can be employed for the stated purpose is an ester of a sulfonated bi-carboxylic acid (U. S. Patent 2,028,091) occurring as a solid named Aerosol OT-'100% (dioctyl sodium sulfosuccinate, see the Bulletin of the National Formulary Committee; Aug-Sept. 1942) and made up by the manufacturer as a1 free-pouring liquid'in various concentrations and is described by the manufacturer as comprising Aerosol 0T 100%, water, and a mutual solvent.

The total quantity of an oily material or wetting agent necessary to eiect the preferred change in the bulk density of a mixture of coking coals for forming a coke-oven charge can beadded to` one of the component coals before its admixture with other coals, or breeze, or the like, to form a charge, and the end effect in the admixture is y substantially the same as though it were applied to the entire mixture. Thus a coal that has been treated wtih the proper amount of oil at the mine can be used in' admixture with an untreated coal to form a coke-oven charge of adjusted bulk density. This addition of an oil to `a coal, at any preferred point, otherthan just before the hammer mill does not diminish the effectiveness of the oil to produce the. stated novel results if there is compensating addition for any deficiency due to anyQin-between operations to which the coaLmay besubjected, such as transportation, storage, crushing, handling or the like, any deficiency inthe preferred quantity of an oil being corrected by adding further small and regulable quantities of the same 'or a different oil or even of a wetting agent previous to the treatment of the coal in the hammer mill. A coal, after the preferred oil treatment, need not be carbonized.

immediately but can be stored, the admixed oil offering some added protection against a' further increase in the superficial-moisture content of the coal charge. i

The following specific examples show results obtained in large-scale operation by the practice oi the present improvement.l

Example 1 At a by-productcoke-oven plant, moisture variations brought about substantial changes in the weight of coalmix it was possible to include in,

tering device controlled the quantity of oil added to the coal mixture, said metering means being provided with an automatic cut-off to arrest the flow of oil when the coal feed was interrupted.

The coal mixture, after addition of the oil, passed through the hammer mill and over conveyor belts to storage bins from which it was discharged to larry cars forA charging to thecoking ovens. A

larry car weighing device supplied the actual weight of coal charged to each oven; however, more immediate control oi' variations in bulk density from-the preferred figure was exercised by the presence of means, directly after the hammer mill, for determining cubic-foot weights oi the oil-treated coal-mix.

Empirical data were first obtained, by the. i methods previously described, to determine the quantity of the preferred oil necessary to be added, because of variations in moisture content of this particular coal-mix, to yield the preferred weight of an oven charge, namely 12.40 ne't tons. These data were required to specifycorrect sizes of the oil pump, pipe line, control valveand metering device for the oil-addition system. It was found that' said preferred weight for an oven charge corresponded to a weight of 41 pounds per cubic foot of said charge, measured in a standard cubic-foot box. Variations in either direction from this cubic-foot weight, as shown by the weights of samples ofthe treated coal-mix taken from the conveyor beit at a point after the hammer mill, were quickly corrected by resetting the svalve which controlled the" rate of oil flow to the coal\ mix entering the hammer mill.

Having described the means employed at this by-product coke-oven planttfor controlling oil additions to the coal-mix and thereby assuring coklng-charges of substantially uniform vweight regardless of their moisture content, we can' now examine actual records oi' results thereby obtained .and compare them with those taken from records of previous operation without oil additions. These contrasting records were taken from the coke-oven operating sheets li'or the same twomonths period in successive years and are illustrated in Figures 2, 3 and 4,s

As hereinabove mentioned, in practical operations prior to the present invention, coke-oven charges could not, from day-to-day, be made of uniform weight because of variations inthe moisture content of the coal, which altered -its bulk density. Curves V and VB of Figure 2 clearly demonstrate this fact. The curve V, the solid line, shows the operation without the use of oil and traces the daily variations in net tons of coal it was possible ,to include in a charged, levelled oven and which ranged from about 11.90 to 12.40 tons Der oven, whereas the preferred weight was 12.40 tons. The curve VB, the broken line, shows that the'iluctuations in moisture content of said coal charges were from about 2.5 per cent to about` 6.5 per cent, the latter being largely responsible for the variations in the weights of the levelled oven charges. The said curves V and VB illustrate the inverse relationship that generally exists between the moisture content of the coal and the Weight of coal that -it is'possible to charge to an oven; that is, as the moisture content of the said coal-increases, the weight per oven charge decreases.

` The curves in Figures 3 and 4 show the cokeoven operation in the same plant for the same l calendar period of the following year, while using oil according to the present improvement. Curve VI, the broken line, shows the fluctuations in the moisture content of the coals actually treated with oil beforetheir charging into the ovens, the fluctuations ranging from about 3 per cent to about 8 per cent and being even 'greater than those shown in curve VB. Oven charges formed of this untreated coal Would. clearly have varied in their weights to an even greater extent than shown in curve V.V Curve VI the s olid line, shows the very small amounts of oil, ranging from nearly zero to only about 0.15 per cent by weight of the coal, that'were added to the to-be-charged coals, having the moisture contents shown in curve VI, and in the manner hereinabove described. The said curves VI and VII demonstrate that, in general, a direct relationshipv exists, between the moisture content of ai coal and the amount of oil that is necessarily added to' maintain it at a constant bulk density, namely, that as the moisture content'of the coal increases ordecreases, the

amount of oil that must be added respectively also increases ordecreases.

Curve VIII of Figure 4 graphically illustrates the remarkable uniformity in the day-to-day weights of oven charges achieved at this coke' oven plant by the practice 'of the present invenf tion, despite Wide fluctuations in the moisture content of said charges. Ibetween this controllable uniformity of weights of oven-charges, as shown by curve VIII, and the very irregular and largely uncontrollable iiuctua-` tion in. the Weights of substantially similar but i untreated coal-charges, as shown by curve V, would be more obvious were one mentally to superimpose Figure 4 upon Figure 2 so that the topmost lines parallel to the' axis of ordinates, namely those representing a value of 12.40 net tons, coincided for both said figures.

Regardless of the day-tQ-day variation in the coals charged,1 whether they were freshly` mined or stock coals previously exposed to rain or snow, this particular by-product coke-oven plant substantially uniformly maintained its oven charges at the preferred weight of 12.40 tons. As a direct result thereof agreater uniformity was achieved in the produced quantity and quality of the coke,

gas and other by-products and the temperatures of the oven heating ilues-were at a constant preferred level.

easily maintained covery of the present invention, the bulk density of the to-be-charged coal was ladiusted to yield The startling contrast a substantially increased weight of coal-charge per oven by additions thereto of debenzolized absorbent oil from the light oil recovery plant. Absorbent oil is a petroleum-derived oil having a specific gravity of about 0.87 to 15.5 C. and a viscosity (Saybolt Universal) of about 80 seconds of a wetting agent and conversely when the moisture content is above one per cent, the same amount of wetting agent increases the bulk density.

From the above-given it is apparent that the present invention provides a number of novel uses and advantages. By the addition of preferred quantities of less than substantially one moisture content there was added 312 per cent by y* Weight of the said debenzolized absorbent oil, said addition producing oven charges that averaged 36,340 pounds per charge, an increase of more than a half ton above the normal weight. The average weight of oven charges increased to 37,150 pounds with the addition of ris per cent by weight of oil to the same coal mixture. When 1/8 per cent by weight of said oil was added, it produced anaverage oven charge of 38,550 pounds, an increase of more than one and a half tons above the normal weight of oven-charges to which no oil had been added. At this plant, by means of additions to the coal of debenzolized absorbent oil Within the range of al; per cent to 1/e per cent by weight, the amount of coal charged into and Acarbonized in the coking ovens, was thus regulably increased.

Example 3 In a manner similar to that previously described, empirical determinations of bulk densities were made on coking-coal charges after admixing therewith, in the form of a 60 per cent solution, of fromy 0.05 per cent to 0.5 per cent by Weight of the coal of a commercial wetting agent. The so-treated coking-coal charges, prior to the additions of wetting agent, differed only in their moisture contents, which were 0.4 per cent and 3.6 per cent. The commercial wetting agent employed was an ester of a sulfonated bicarboxylic acid (U. S. Patent No. 2,028,091). It is a solid known in the trade as Aerosol 0T 100% (dioctyl sodium sulfosuccinate, see the Bulletin of the National Formulary Committee; Aug-Sept. 1942), and is made up by the manufacturer as a freepouring liquid in various concentrations. The material employed in the present instance is described by the manufacturer as comprising 60% of Aerosol OT 100% in water and a mutual solvent. The following table shows the results of the. empirical determinations on two coking charges after the indicated quantities of this wetting agent, calculated to the dry material, had been admixed therewith.

creased in bulk density by addition of a solution per cent by weight of an oily material or a wetting agent to a coking coal having a moisture content in excess vof one per cent, the bulk density of said coking coal can be materially increasedl thereby enabling the coke-plant operator to charge a greater average weight of coal to his individual coking chambers Where maximum coke production is required. This is of particular advantage and a `direct source of increased revenue, for example, in a plant where higher-moisture-containing washed coals are usually carbonized. By simple, empirical tests it is possible also to determine the exact quantities of an oil, or wetting agent, or the like, necessary to be added to coking charges to obtain substantially uniform bulk densities when said coking charges vary in their moisture contents. By these means the cokeplant operator can maintain his coke-oven charges substantially uniform from day to day regardless of weather conditions, which formerly caused wide fluctuations in the coal tonnage charged. By

stabilizing the daily quantity of coal charged, it is much easier to secure uniformity not only in the heating of the oven chambers and general oven operations but in the operation of all other byproduct units in the plant. Uniform heating obviously results in an improved coke-product and in lower maintenance costs for oven operation. Because of low cost and general availability in a coke-oven plant, low-viscosity oils are preferred to produce the beneiicial results. It is to be understood however that other oily vmaterials of varying and higher viscosities and so-called wetting agents can be used if preferred. When a coking charge is a mixture comprising coals and/or other vcarbonaceous materials the preferred quantities of ,an oil required for said coking charge can be added to one component of said charge before its admixture with the other components. In those exceptional cases Where dry or slightly moist or dangerously expanding coals must be charged, it is possible to employ the above-described methods to bring' about a decrease in the bulk density of said coals.

The invention as hereinabove set forth is embodied in particular form and manner but may be variously embodied within the scope of the lof nnely pulverized coal having both a moisture content of less than eight percent by weight-and upon delivery to said ovens a bulk density precluding normally forming said oven-charges or a prescribed weight nof said coal, said process comprising: altering the bulk density of said deliv- '.ered finely pulverized coal aforesaidbefore chargin g -tha same into divers ovens ofthe coke-oven battery, by'treatment comprising distributing over the finely pulverized coal to be charged sumclent amount of a mobile oil that is less than substantially onehalf of one percent by weight of said coal and by said treatmentl furnishing the ilnely pulverized oil-treated coal with a bulk density such that a prescribed weight of the finely 'pulverized coal can be normally charged into said o/vens, and thereafter/charging thesame into divers ovens of the coke-oven batterywand coking 3. A process of preparing' for and coking in divers ovens ofa coke-oven battery avena-charges of nely pulverized coal having both a moisture concontent of less than-eight percent by weight and upon delivery to said ovens a bulkv density precluding normally forming said oven-charges of a prescribed substantially uniform weight of said coal for the divers said ovens, said process comprsing altering the bulk density of said delivered finely pulverized coal aforesaid beforecharging the same into divers ovens of the coke-oven batmitting said prescribed weight of the finely pulverized oil-treated coal vnormally to be charged into the ovens uniformly, and thereafter charging oven batteryand coking the same therein.

' such oil-treated coal into divers ovens of the coketent between one percent and eight percent by weight and upon delivery to said ovens a bulk density precluding normally forming said ovencharges of a prescribed weight of said coal, said process comprising; increasing the buik density of said finely pulverized coal aforesaid before charging the same into divers ovens of the coke-oven battery by treatment comprising distributingr over the finely pulverized coal to be charged sumcient amount of a mobile oil that is less than substantiallyvone-half of one percent by weight of said coal and furnishing by said treatment the nely pulverized oil treated coal with an increased bulk density such that a prescribed weight of the finely pulverized coal can be normally charged into said ovens, and thereafter charging the same into divers ovens of -the coke-oven battery and coking the same therein.

FREEMAN DOOLI'I'ILE LO GILBERT VINCENT MCGUR 

